Thanks for the suggestions John. I will certainly consider this quite seriously.
Regards – Grant. 201496 (Internal phone) +44 (0)2076501496 (External phone) -----Original Message----- From: IBM Mainframe Assembler List [mailto:ASSEMBLER-LIST@LISTSERV.UGA.EDU] On Behalf Of John McKown Sent: Friday, November 11, 2016 12:58 PM To: ASSEMBLER-LIST@LISTSERV.UGA.EDU Subject: Re: Question on using DYNALLOC On Fri, Nov 11, 2016 at 6:33 AM, Ward Able, Grant <gwarda...@dtcc.com> wrote: > Ah rats! Looks like I am going to have to use a new member name every > time. Thanks Paul. > Now to code up a member name lookup piece of code...... > I think the following will work. Allocate the DSN(MEMBER) with a DISP=OLD (for integrity) or SHR (if it's a PDSE or you're a gambler). Now, do an OPEN on _two_ different DCBs for the DD. First OPEN a DCB for _input_. Then OPEN a second DCB for _output_. When you OPEN a member of a PDS for _output_, the access method always positions to write at the end of the PDS, into "unused" space. You can now read records from the INPUT DCB and write them immediately to the OUTPUT DCB. At EOF on the input DCB, close the input DCB. Continue writing the new information to the output DCB. Finally, close the output DCB. This will do a STOW to actually update the PDS directory so that the member name now points to the new version of the member. Until the output DCB is closed, the PDS directory continues to point to the old member. But remember that an ABEND will do a close and _will_ update the directory so you _could_ loose the original member contents. What I'd suggest doing is similar to what you indicated, use a new member name. Being a weird-o. Remember that all member names are exactly 8 characters in length! The ones that look shorter are actually padded on the right with blanks. Also, remember that all byte combinations, with the exception of 8X'FF' are valid as a member name, though the non-printables can't be used in JCL or TSO ALLOCATE or BPXWDYN. So, weird person that I am, I would use SVC 99 (which I am fairly sure will accept non-printables as a member name) as you do above but make the member name be equal to the original member name, with the last character being X'00'. Now copy the original contents to the new member. Eventually you will close both the input & output DCBs successfully. Now, allocate the same DSN, but without a member name. Open a BPAM DCB on this, rather than the "normal" QSAM / BSAM you would for a member. Use a STOW delete function to delete the original member name. Lastly use a STOW rename to change the "weird" member name to the original member name. I, personally, feels that this is the safest way to "update" a member of a PDS without coming up with a "new" name all of the time. Of course, my method is a bit on the paranoid side. But, remember, just because you're paranoid doesn't mean that they aren't out to get you. Bugs, that is. And, it was just a weird idea (from a grand master). > > > > Regards – Grant. > > 201496 (Internal phone) > +44 (0)2076501496 (External phone) > > -- Heisenberg may have been here. Unicode: http://xkcd.com/1726/ Maranatha! <>< John McKown DTCC DISCLAIMER: This email and any files transmitted with it are confidential and intended solely for the use of the individual or entity to whom they are addressed. If you have received this email in error, please notify us immediately and delete the email and any attachments from your system. The recipient should check this email and any attachments for the presence of viruses. The company accepts no liability for any damage caused by any virus transmitted by this email.
